Trick codegen into generating getfield from the anonymous class instead
of its supertype (e.g. kotlin.jvm.internal.FunctionReference,
PropertyReference or AdaptedFunctionReference). This gets rid of
unnecessary accessors in some cases, and will help in the subsequent
commit that changes logic around access to fields from Java
superclasses.
This is needed for the inliner: since the information about Kotlin type
of the bound receiver is nowhere in the output binary, the inliner will
have no clue how to box inline class values. Moving the boxing outside
the object means the inliner doesn't need to know about it; from its
point of view, the captured value has type `Any`.
Alexander Udalov